Electrical contact retaining device

ABSTRACT

A switch having contacts which may be inspected, cleaned and replaced without the danger of removing and losing small hardware items. The switch contact arm is held in place by a spring loaded key keeper with the arm and switch block each keyed 90* apart. Rotation of the keeper to remove the arm orients it so that it will not slip through the block and become lost.

UnitedStates Patent Wallace et al. Apr. 17, 1973 ELECTRICAL CONTACT RETAINING 5 References Cited DEVICE N UNITED STATES PATENTS [75 Inventors: Richard M. Wallace, Kirkwood;

3 597 562 8/1971 Tumbull ..200/166 BC Snyder Chenang" 3 359 395 12 1967 B 200 166 BH g both OfNIY. ruce Primary Examiner-H O. Jones [73] Assignee: 32h? Singer Company, Bmghamton, Atmmey FranciS L Massene et [22] Filed: July 14, 1972 [57] ABSTRACT Appl. No.: 271,801

US. Cl ..200/166 BC Int. Cl. ..H01h 1150 Field of Search ..200/ 166 BC, 166 BH, 200/166 .l

A switch having contacts which may be inspected,

cleaned and replaced without the danger of removing and losing small hardware items. The switch contact arm is held in place by a spring loaded key keeper with the arm and switch block each keyed 90 apart. Rotation of the keeper to remove the arm orients it so that it will not slip through the block and become lost.

5 Claims, 1 Drawing Figure ELECTRICAL CONTACT RETAINING DEVICE BACKGROUND OF THE INVENTION This invention relates to switches in general and more particularly to a switch which permits the removal, inspection, cleaning and replacement of contacts without the hazards of inconvenience of loose hardware.

In the majority of prior art switches contact removal for inspection, cleaning, replacement and the like requires the removal of screws, nuts, and bolts, etc. These are generally of a small size and prone to becoming lost and possibly, in complex switching equipment such as a traffic controller unit, falling into spots where they can cause short circuits. Thus there is a need for a switch which minimizes the hazards involved and also the down time involved in contact removal.

SUMMARY OF THE INVENTION The present invention fills the need for such a switch through the use of a unique keying system in which contacts are held in place by a spring loaded key keeper. Removal of the contact arm is accomplished by rotating the keeper so that it will slip through a slot in the arm. The keeper and spring will not come loose in this position since the switch block is slotted in a direction requiring a further 90 rotation.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE is an exploded perspective view of a preferred embodiment of the switch.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the FIGURE, the switch comprises a block 11 having mounted thereon a terminal plater l3 and contact plate 15, a contact arm 17, a spring 19 and a key keeper 21. Keeper 21 has a large end 22, a narrow center section 24 and a small end' 26. A portion of center section 24 contains protrusions 28 which form a key. The spring 19 is slipped over the small end 26 of keeper 21 and is retained by large end 22. Keeper 21 is then inserted through a keyed hole 23 in block 13. The circular portion of hole 23 has a diameter slightly larger than that of section 24 and the keyed portion is slightly larger than end 26 and key 28. The keeper is then rotated 90 with spring 19 held compressed and the arm 17 slipped over its end through hole 25. The keeper is again rotated 90 so that the key 28 will prevent arm 17 from slipping off the end. Spring 19 keeps contacts 27 and 29 in electrical contact with terminal plate 13 and contact 31 on contact plate respectively.

Removal of the arm 17 for inspection, cleaning or replacement is accomplished by compressing spring 19 and rotating keeper 21 90. Since the slots in keyholes 23 and 25 are 90 apart, keeper 2] is now in a position from which it cannot slip through block 11 and become lost. The only free part is arm 17, the part which must be inspected, cleaned or replaced. Contact plate 15 is slotted at the top so that it can be replaced by only loosening a screw 33 and sliding it out. (It is available for cleaning or inspection as soon as arm 17 is removed.) Switch operation is effected by cam 35 gushing against arm 17 and separating contacts 29 and l which WIII cause arm 17 to rotate about contact 27 in the direction shown by arrow 37 and further compress spring 19. Since contact 17 and terminal plate 13 are always in contact, the plate 13 should not wear and should never need be replaced.

Operation of the switch by cam 35 is shown only as an example. It will be obvious to those skilled in the art that other means of operation may be employed. Other modifications may similarly be made without departing from the spirit of the invention which is intended to be limited solely by the appended claims.

What is claimed is:

1. A switch in which the contact retaining device prevents loose hardware when servicing the switch, comprising:

a. switch block containing a keyed hole and having mounted on it at least one contact;

a contact arm containing at least one contact and having a similar keyed hole which, when aligned with the keyed hole in said block, will cause said blockcontact and said arm contact to be aligned, the keyed hole of said arm having its keyed portion at a different angular rotation from the keyed portion of the keyed hole in said block;

vc. a key keeper having a first end substantiallylarger than said keyed holes, a center portion of a size substantially equal to but smaller than the circular portion of said keyed holes and a second end having protrusions substantially matching the key portions in said keyed holes, said keeper having a spring slipped over its second end and said keeper inserted through said keyed hole in said block and said keyed hole in said arm and rotated to a position where said protrusions will prevent said arm from sliding off said keeper with the spring force holding said arm contact against said block contact, whereby, when said keeper is rotated to remove said arm, the keeper and spring will be oriented so that they will not slip out of said block due to the different angular orientation of said keyed portions of said keyed holes.

2. The invention according to claim 1 wherein there is mounted on one side of said block a contact plate on one side of said keyed hole and a terminal plate on the other side of said keyed hole and said arm contains two contacts which are aligned respectively with said contact plate and said terminal plate, wherein operation of said switch may be effected by pushing said arm so that the one contact on said arm is moved away from said contact plate, thereby causing said arm to rotate about said second contact at said terminal plate.

3. The invention according to claim 2 wherein said switch is operated by a cam.

4. The invention according to claim 2 wherein said contact plate is slotted on one end and is attached to said block by means of a screw passing through said slot and secured to said block, whereby said screw need only be loosened to remove said contact plate.

5. The invention according to claim 1 wherein said block keyhole and arm keyhole are oriented so that their respective keyed portions are apart. 

1. A switch in which the contact retaining device prevents loose hardware when servicing the switch, comprising: a. switch block containing a keyed hole and having mounted on it at least one contact; b. a contact arm containing at least one contact and having a similar keyed hole which, when aligned with the keyed hole in said block, will cause said block contact and said arm contact to be aligned, the keyed hole of said arm having its keyed portion at a different angular rotation from the keyed portion of the keyed hole in said block; c. a key keeper having a first end substantially larger than said keyed holes, a center portion of a size substantially equal to but smaller than the circular portion of said keyed holes and a second end having protrusions substantially matching the key portions in said keyed holes, said keeper having a spring slipped over its second end and said keeper inserted through said keyed hole in said block and said keyed hole in said arm and rotated to a position where said protrusions will prevent said arm from sliding off said keeper with the spring force holding said arm contact against said block contact, whereby, when said keeper is rotated to remove said arm, the keeper and spring will be oriented so that they will not slip out of said block due to the different angular orientation of said keyed portions of said keyed holes.
 2. The invention according to claim 1 wherein there is mounted on one side of said block a contact plate on one side of said keyed hole and a terminal plate on the other side of said keyed hole and said arm contains two contacts which are aligned respectively with said contact plate and said terminal plate, wherein operation of said switch may be effected by pushing said arm so that the one contact on said arm is moved away from said contact plate, thereby causing said arm to rotate about said second contact at said terminal plate.
 3. The invention according to claim 2 wherein said switch is operated by a cam.
 4. The invention according to claim 2 wherein said contact plate is slotted on one end and is attached to said block by means of a screw passing through said slot and secured to said block, whereby said screw need only be loosened to remove said contact plate.
 5. The invention according to claim 1 wherein said block keyhole and arm keyhole are oriented so that their respective keyed portions are 90* apart. 